class Circle{
  constructor(r){
    this.#radius = r;
  }
  get area(){
    return Math.PI * this.#radius * this.#radius;

  }
  //通过get让函数变成属性
  get circumference(){
    return Math.PI * this.#radius * 2;
  }
  #radius = 0;
}

module.exports = Circle;
 
